Casings for joists, columns and other structural members

ABSTRACT

A fireproof casing for a steel joist with flanges including a number of precast concrete blocks formed with interengaging undercut surfaces to interlock around the joist and each block capable of being positioned transversely on the joist and of interlocking with the other blocks by longitudinal movement. The interlocking surfaces of the blocks are tapered to provide a wedging effect and in one embodiment the blocks are arranged to support further horizontal joists purely in compression against a flange of the main joist.

United States Patent inventors George Molyneux:

George Walter Molyneux, both 01 Eastbrook Road, Gloucester, England Appl. No. 769,234

Filed Oct. 21, 1968 Patented July 6, 1971 Priority Oct. 25, 1967, Nov. 30, 1967, Feb. 9, 1968 Great Britain 48433/67, 54439/67 and 6468/68 CASINGS FOR JOlSTS, COLUMNS AND OTHER STRUCTURAL MEMBERS 5 Claims, 18 Drawing Figs.

U.S. C1 52/728, 52/725, 52/731 Int. Cl E04c 3/293, E04c 3/34 Field of Search 52/725, 594, 728, 727, 726, 731, 492, 594, 725

References Cited UNITED STATES PATENTS 2,016,382 10/1935 McBurney 52/594 2,580,174 12/1951 Henderson 52/594 219,120 9/1879 Schreiel 52/726 338,512 3/1886 Gi1man.. 52/725 2,074,463 3/1937 Davisw. 52/725 2,664,739 1/1954 Marcy 52/725 FOREIGN PATENTS 672,330 3/1966 Belgium 52/725 550,434 H1943 Great Britain 52/725 674,353 1929 France 52/728 2,449 10/1861 Great Britain... 52/727 105,191 1916 Great Britain 52/731 Primary Examiner-Henry C. Sutherland Attorney- Young and Thompson ABSTRACT: A fireproof casing for a steel joist with flanges including a number of precast concrete blocks formed with interengaging undercut surfaces to interlock around the joist and each block capable of being positioned transversely on the joist and of interlocking with the other blocks by longitudinal movement The interlocking surfaces of the blocks are tapered to provide a wedging effect and in one embodiment the blocks are arranged to support further horizontal joists purely in compression against a flange of the main joist.

PATENTED JUL 6 I97! SHEET 2 BF 2 Games Mum/fax GEORGE WeLraP MQ y/VAW l' INVENTOR? ATTORNE YS CASINGS FOR .lOllSTS. COLUMNS AND O'llllllER STRUCTURAL MEMBERS a casing formed of brickwork, concrete, asbestos, cement, or

other fire-resistant material. These casings are normally formed by fabricating a shuttering around the joist or column, and then pouring in liquid concrete. The construction of such shuttering, and the pouring of the concrete, are laborious time-consuming operations. Moreover in the case of horizontal joists it is frequently difficult to support the shuttering while the concrete is poured. Accordingly it is one object of the present invention to provide an improved casing, and component elements therefor, which can readily be placed in position and located on a joist, column or other structural member, without the need for shuttering or other supports and preferably in such a manner that the individual parts of the casing are firmly and positively located.

From one aspect the invention consists in a casing for a joist, column, pillar or other structural member, or part thereof comprising a number of interengaging shell members, formed to interlock with one another or with further locking members so that when assembled they are prevented from displacement laterally with respect to the member.

Preferably the shell members are capable of being positioned on the structural member by transverse lateral movement with respect thereto. Also according to a preferred feature of the invention the shell members, and/or locking members, are formed to interlock by relative longitudinal movement.

According to another preferred feature of the invention the shell members, and/or locking members, are provided with tapered interengaging surfaces acting as wedges to provide tight locking engagement on relative longitudinal movement.

In some forms of the invention the shell members are adapted to engage with further shell members spaced longitudinally along the structural member, the said engaging shell members being formed with cooperating rebated or counten sunk surfaces to provide a degree of overlap and avoid an open joint through the casing.

In any case the shell members are preferably formed of a fireproof or fire-resistant material, and conveniently are formed as cast or moulded components of concrete, or other cementitious material, usually with built-in metal reinforcement.

As stated the invention is particularly applicable to steel structural members and can be applied with advantage to such members having a web and a perpendicular flange. In such cases the casing preferably includes a yokeshaped shell member fitting partly around the flange, and two further shell members or locking pieces positioned on opposite sides of the web and engaging formations on the yoke to hold the parts in position on opposite sides of the web and flange.

According to a preferred feature of the invention the members on opposite sides of the web may project beyond the edges of the yoke and act as supporting abutments for further structural members.

In any case the yoke preferably has an opening of greater transverse width than the width of the flange and undercut for mations on each side of the opening, and each of the further shell members or locking pieces is adapted to engage against the opposite face of the flange and has cooperating projecting formations to engage with the said undercut formations.

The casing may be designed to enclose the structural member totally, but in some cases part of the structural member may already be encased or embedded in another part of the building structure, such as a wall or floor, and the casing may therefore be arranged to enclose only part of the structural member.

The invention also consists in a method of applying a casing to a structural member in which a number of interengaging shell members, formed to interlock with one another or further locking members, are assembled around the structural member and interlocked by relative longitudinal movement so that they are prevented from being displaced laterally.

The invention also resides in the individual shell members for use in performing the invention.

The invention may be performed in various ways and a number of embodiments will now be described by way of example with reference to the accompanying drawings, in which:

FIG. 11 is an end view of a casing according to the invention in position around an I-section steel joist,

FIG. 2 is a perspective view of the structure of FIG. 1,

FIG. 3 is an end view of a slightly modified form of casing,

FIG. 4 is a fragmentary end view on an enlarged scale showing a modified form of Z-locking formation,

FIG. 5 is a perspective view showing a casing as illustrated in Flt]. It or FIG. 2; applied to the construction of a reinforced concrete column,

FIG. 6 is an end view of an alternative form of easing,

FIG. "I is a vertical sectional elevation through the casing of FIG. 6:, with the internal structural member omitted,

FIG. 8 is a perspective view of the casing of FIGS. 6 and 7 with the structural member omitted,

FIG. 9 is a perspective view of a somewhat similar but modified form of easing, again with the structural member omitted,

FIG. i0 is a sectional end elevation through a further modified form of casing according to the invention, surrounding an l-section steel joist,

FIG. llll is a vertical sectional elevation through the lower yoke member of the construction of FIG. 110,

FIG. i2 is a similar view to FIG. ll ofa modified form of the yoke member,

FIG. 113 is a sectional end elevation through an I-section structural member having its upper flange embedded in a floor and its lower flange and web encased by a casing resembling that ofFIG. 10,

FIG. M is a sectional end elevation of an I-section girder, with a casing similar to that of FIG. 13, but arranged to support horizontaljoists,

FIG. I5 is a part-sectional end elevation ofa further form of casing according to the invention as applied to the lower part of the web and lower flange of an l-section girder,

FIG. I6 is a sectional side elevation through the lower yoke member of FIG. ll, and

FIGS. 17 and 118 are sectional end elevations through two further modified forms of easing according to the invention.

In the casing construction illustrated] in FIGS. 1 and 2 the casing is formed by a number of pairs of precast concrete shell members lltl and Ill positioned end-to-end along the length of a structural member 12, which in this instance is an I-section steel girder, so as to form a complete casing totally enclosing the girder. The two shell members It) and ll of a pair have longitudinally extending abutting surfaces 13 which are of Z- form in transverse cross section as seen in FIG. 1. Each shell member is generally of channel shape and the width of the channel is slightly greater than the width of the flanges of the girder 12. Thus each shell member can be positioned over the respective flange by movement in a transverse lateral direction, that is to say by moving the upper shell member downwards over the upper flange, and the lower shell member ll upwards around the lower flange. In assembling the casing two such shell members 10 and H of a pair are initially positioned at different longitudinal stations, the Z-formations of the two shell members are then aligned, and one shell member is moved longitudinally relative to the other to cause the Z- formations to interlock as shown in FIGS. 1 and 2. When so assembled the two shell members are interlocked and positively prevented from transverse lateral movement with respect to the steel structural member, To increase the strength of the precast shell members internal reinforcing as illustrated at 14 is incorporated in each shell member, extending into the undercut parts thereof which provide the Z-formation.

In the modified form of easing as illustrated in FIG. 3 the two Z-formations are positioned asymmetrically with respect to the horizontal centerline through the section. If desired the abutting surfaces 13, which form the Z-formation, may be tapered towards one end of the respective shell member to provide a V-section groove 15, see FIG. 4, which is of advantage in initially aligning the Z-formations during assembly. Subsequently this groove 15 may be filled with a cement grouting. It will be understood that other forms of undercut interlocking locating formations may be adopted in place ofa Z- shape. For example an S-formation or a dovetail formation may be adopted.

In the construction illustrated in FIG. 5 pairs of casing members 10,11, similar to those illustrated in FIGS. 1 and 2, are assembled and erected to form a hollow vertical rectangular casing and this is subsequently filled with liquid cement indicated generally at 16, in which are embedded a number of reinforcing rods 17.

In the further modified form of casing illustrated in FIGS. 6, 7 and 8, the casing is formed by a number of pairs of shell members 20,21. In this case the abutting surfaces 22 between each pair of shell members are flat. Each shell member is formed at one end with a projecting rectangular section rib 23, which together form a rectangular frame supporting the central aperture, and with a corresponding rebate or recess 24 at the opposite end, affording a socket to receive the corresponding rectangular frame formed by the next adjacent pair of shell members 20,21. The pairs of shell members 20,21 are positioned longitudinally with their abutting surfaces 22 alternately horizontal and vertical as shown in FIG. 8. Thus when located each pair of shell members is itself located by the next adjacent pair of shell members so that the complete casing cannot be removed transversely from the structural member enclosed. In this construction it is of advantage for the shell members to be of square cross section so that identical shell members can be used along the length of the structural member. If necessary however the shell members may be of nonsquare cross section in which case alternate pairs of shell members must be of special proportions.

In the alternative construction illustrated in FIG. 9 the ribs 23 on each shell member are replaced by projecting pegs of studs 28, and the opposite end of each shell member is formed with corresponding sockets to receive the studs on adjacent shell members. This construction has the advantage that both ends of each shell member are positively located.

In the further form of the invention illustrated in FIGS. 10 and 11 a casing for an I-section steel girder 30 comprises upper and lower yoke-shaped shell members 31,32 and a pair of blocks 33,34 positioned on either side of the web of the structural member. Each yoke-shaped member has a flat surface 35 to engage the outer face of the respective flange of the steel member and two wings 36,37 which extend around the flange generally parallel to the main web 30. These wings 36,37 have inward projections 38,39 which define undercut surfaces 40. Each of the blocks 33,34has corresponding outward projections with surfaces which mate with these undercut surfaces 40. As shown in FIG. 11 the undercut surfaces 40 are preferably tapered or inclined lengthwise, and the corresponding mating surfaces on the block 33,34: are likewise inclined in this direction.

To assemble the shell members around the structural member the two yoke shell members 31,32 are first positioned as shown in FIG. 10 and the two block members 33.34 are then placed in position on opposite sides of the web 30 at a point longitudinally displaced from the yoke members 31,32. The block members 33,34 are then moved longitudinally to that their outward projections engage the undercut surfaces 40 and continued longitudinal movement along these inclined surfaces causes a wedging action which holds all the shell members 31, 32, 33, 34 in tight engagement around the steel member. The shell members 31,32 include internal reinforcement 41 for added strength and as shown in FIG. 11 the yoke members may be formed with projecting ribs and rebated end formations similar to those illustrated in FIGS. 6, 7 and 8, in

order to provide overlapping engagement with the next shell members positioned along the length of the casing, and so avoid a direct joint through to the steel structural member.

FIG. 12 illustrates a possible modification of a yoke shell member, similar to that of FIGS. 10 and 11. In this case the inward projection 38 on the wing 36 is replaced by three lugs 43 each having an inclined undercut lower surface 44. The lower part of the block members, corresponding to the block members 33,34 of FIG. 10, will be formed with corresponding spaced lugs having inclined outer surfaces to engage with the inclined surfaces 44. By comparison with the construction of FIG. 11 this arrangement provides a similar wedging effect with a smaller longitudinal movement.

In the construction illustrated in FIG. 13 an I-section steel girder has its upper flange 50 embedded in a concrete floor structure 51. The lower flange 52 and the web 53 of the girder are encased by a construction similar to that of FIGS. 10 and 1 1 and comprising a yoke member 54, a pair of locking blocks 55,56 having surfaces which engage against the undercut surfaces on the yoke member, and masonry or precast filling blocks 57,58.

In the construction illustrated in FIG. 14 the upper flange 60 of an l-section steel girder is embedded in a concrete floor 61 and the flower flange 62 is encased by a yoke member 63 and a pair of locking blocks 64,65 similar to the construction of FIG. 13. It will be noted in particular that the blocks 64,65 extend somewhat above the upper level of the wings of the yoke member 63. On each of these locking blocks 64,65 is supported one end ofa horizontal steel joist 66, and it will be noted that the weight of the joist is transferred under compression through the respective locking blocks 64,65 onto the lower flange 62 of the structural member, and does not impose any strain upon the undercut surfaces or other parts of the yoke member 63. The space above the horizontal joist 66 is filled by masonry or other cast concrete blocks 67.

The construction of casing illustrated in FIGS. 15 and 16 is in principle somewhat similar to the construction of FIG. 10. FIG. 15 shows this construction applied as a casing to the lower part of a vertical web 70 and a lower flange 71 of an I- section steel member. The casing comprises a lower yoke member 72 and a pair of upper locking members 73,74. The yoke member 72 has upwardly projecting wings 75 extending on either side of the flange 71, but by comparison with the construction of FIG. 10 these wings have upper surfaces which are inclined generally at 45 from the horizontal. Each of these inclined surfaces includes a lower part 76, a step 77, perpendicular to the surface 76, and an upper surface 78. It will be noted that the step 77 is therefore inclined inwardly towards the web 70 at an angle of 45 from the horizontal. Also as seen in FIG. 16 the step 77 is inclined longitudinally, being lower at one end of the yoke member, and higher at the other end.

Each of the block members 73,74 is shaped to engage the inner surfaces of the web 70 and lower flange 71 of the structural steel member, and has similar inclined surfaces to cooperate with the surfaces 76, 77, 78 on the yoke member.

Thus to assemble the casing as shown in theseFIGS. 15 and 16, the yoke member 72 is first raised into position against the lower flange 71 as shown in FIG. 15, the locking members 73,74, are then positioned on opposite sides of the web member, at a point displaced longitudinally with respect to the yoke member 72, and the locking members 73,74 are then moved longitudinally so that they engage with the surfaces 76, 77, 78, providing a wedging effect which holds the three parts in tight engagement around the steel member.

Each of the precast concrete shell members 72, 73, 74 is formed with projecting parts at one end, as illustrated at 80, and socket formations at the other end, as illustrated at 81, so that the three parts of the casing overlap and interlock with the corresponding parts of the next adjacent shell members positioned along the length of the steel structural member.

In a further possible modification illustrated in FIG. 17 the casing is applied again to an l-section steel member 85. The casing consists of an upper pair of shell members 86,87 and a similar lower pair of shell members 86,87. Each shell member 87 has a part 88 designed to engage against part of the web of the steel member and the corresponding inner surface of the respective flange. The shell member 87 also has a part 89 engaging against the outer surface of the same flange and a projecting portion 90 with an undercut surface 91. The cooperating shell member 86 likewise has a projecting part 91 to engage the opposite surface of the steel web and the inner surface of the respective flange of the steel member, and a projecting part 93 with an undercut surface which engages with the undercut surface 91. These undercut surfaces may be longitudinally inclined'in the manner illustrated in FIG. 11 or FIG. 16 to provide a wedging effect.

It will be seen that a pair of shell members 86,87 can be introduced laterally into position around the respective flange and part of the web of the steel member, and by longitudinal relative movement the projecting parts 93,90 and the undercut surfaces 91 can then be caused to interlock so as to hold the two shell members 86,87 in position. The remaining two shell members 86,87 can then be similarly positioned and it willbe noted that in the final assembly the shell members 86,87 associated with different flanges of the steel member abut against each other on stepped longitudinal abutment surfaces 94, which thus avoid any open joint through to the structural steel. As in the previous constructions the individual precast concrete shell members are internally reinforced as shown at 95, and the ends of the shell members may be formed with projections and rebates as illustrated in FIGS. 11 and 16,

to interlock with the next adjacent shell members along the length of the structural member.

In the construction illustrated in FIG. 18 the invention is applied again to an I-section steel member 100. In this case the casing comprises a pair of blocks 101 positioned on either side of the steel member but having a width somewhat less than the corresponding width of the flanges 102 of the steel member. The lower flange 102 is encased by a pair of precast concrete members 103 each having an upper part 104 which extends inwards and engages over the upper surface of this flange 102. The shell members 103 have lower parts 105 which project inwards towards one another below the lower surface of the flange 102, each of these projecting parts 105 having an up wardly inclined undercut surface 106. In order to lock the two shell members 103 in position an inner locking member 107 is provided, shaped to engage the undersurface of the flange 102 and also against the undercut surfaces 106.

To assemble the casing the blocks 101 are first positioned around the web 100, the two shell members 103 are then inserted laterally, in a horizontal direction, and finally the locking member 107 is positioned below the flange I02 and slid longitudinally into a position in which it engages with the undercut surfaces 106 on the two shell members 103. Similar parts are then assembled around the upper flange of the steel member.

As in the previous embodiment the individual shell members are internally reinforced and at their opposite ends they are provided with projecting parts and rebated surfaces as illustrated in FIGS. 11 and 16.

It will be noted that in all cases the individual shell members can be positioned around a structural steel member without the need for access at one end of the steel member. In other words the individual shell members can be inserted transversely and laterally with respect to the structural member. For this purpose the yoke members, as illustrated for example in F 16$. and 15, have mouths which are wider than the respective flange of the steel member. Likewise the shell members 86 and 87 as shown in FFG. 17 are arranged to be capable of being inserted over the steel flanges, by a horizontal movement. In some cases however the shell members may be designed for longitudinal assembly on the structural steel member, where conditions permit this to occur.

We claim:

1. A metallic structural member having a web and a perpendicular flange, and a fire roof casing on said member, said casing comprising a plura ity of generally U-shaped fire-insulating shell members extending longitudinally over a limited length of said structural member, each shell member having a surface engaging against the outer surface of said flange, and two wing formations which extend around the opposite edges of said flange and have undercut inwardly directed locking surfaces, anda plurality of fire-insulating locking members, each engaging against the opposite surface of said flange, and against said web, and also having a cooperating locking sur face engaging with the locking surface of an adjacent one of said shell members, the said cooperating locking surfaces on said shell members and locking members extending from end to end of the shell members and locking members and being inclined longitudinally towards the plane of said flange, whereby longitudinal movement of a locking member relative to one of said shell members in position against a structural member moves said inclined locking surfaces upon each other with a wedge action that causes progressively increasing tightening of said locking member and said shell member against the intervening flange of said structural member.

2. A structure according to claim 1, in which the metallic structural member is of I-section having a further perpendicular flange at the other edge of said web, including a further plurality of like shell members arranged to engage the said further flange of said structural member, and to be tightened into engagement therewith by relative longitudinal movement of like fire-insulating locking members formed with inclined locking surfaces.

3. A structure according to claim 2, wherein the shell members engaging the opposite flanges of said structural member are spaced apart from each other, and separated by said locking members.

4. -A structure according to claim 2, wherein said shell members and said locking members contact the whole external surface of said structural member.

5. A structure according to claim 1, wherein said locking surfaces are also inclined both to said web and to said flange thereby to tighten said locking members both against said web and against said flange. 

1. A metallic structural member having a web and a perpendicular flange, and a fireproof casing on said member, said casing comprising a plurality of generally U-shaped fire-insulating shell members extending longitudinally over a limited length of said structural member, each shell member having a surface engaging against the outer surface of said flange, and two wing formations which extend around the opposite edges of said flange and have undercut inwardly directed locking surfaces, and a plurality of fire-insulating locking members, each engaging against the opposite surface of said flange, and against said web, and also having a cooperating locking surface engaging with the locking surface of an adjacent one of said shell members, the said cooperating locking surfaces on said shell members and locking members extending from end to end of the shell members and locking members and being inclined longitudinally towards the plane of said flange, whereby longitudinal movement of a locking member relative to one of said shell members in position against a structural member moves said inclined locking surfaces upon each other with a wedge action that causes progressively increasing tightening of said locking member and said shell member against the intervening flange of said structural member.
 2. A structure according to claim 1, in which the metallic structural member is of I-section having a further perpendicular flange at the other edge of said web, including a further plurality of like shell members arranged to engage the said further flange of said structural member, and to be tightened into engagement therewith by relative longitudinal movement of like fire-insulating locking members formed with inclined locking surfaces.
 3. A structure according to claim 2, wherein the shell members engaging the opposite flanges of said structural member are spaced apart from each other, and separated by said locking members.
 4. A structure according to claim 2, wherein said shell members and said locking members contact the whole external surface of said structural member.
 5. A structure according to claim 1, wherein said locking surfaces are also inclined both to said web and to said flange thereby to tighten said locking members both against said web and against said flange. 